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LSB first) is possible using the MT1379 internal configuration registers. The I2S format
uses four stereo data lines and three clock lines. The PS data and clock lines can be
connected directly to one or more audio DAC to generate analog audio output.
The two-channel DAC is a CS4392, The DACs support up to 192kHz sampling rate.
The outputs of the DACs are differential, not single ended so a buffering circuit is
required. The buffer circuits use National LM833 op-amps to perform the low-pass
filtering and the buffering,
5 VIDEO INTERFACE
5.1 Video Display Output
The video output section controls the transfer of video frames stored in memory to the
internal TV encoder of the MT1379, The output section consists of a programmable CRT
controller capable of operating either in Master or Slave mode.
The video output section features internal line buffers which allow the outgoing
luminance and chrominance data to match the internal clock rates with external pixel
clock rates, easily facilitating YUV 4:2:2 to YUV 4:2:0 component and sample
conversion, A polyphase filter achieves arbitrary horizontal decimation and interpolation.
Video Bus
The video bus has 8 YUV data pins that transfer luminance and chrominance (YUV)
pixels in CCIR601 pixel format (4:2:2), In this format, there are half as many
chrominance (U or V) pixels per line as luminance (Y) pixels; there are as many
chrominance lines as luminance,
Video Post-Processing
The MT1379 video post-processing circuitry provides support for the color conversion,
scaling, and filtering functions through a combination of special hardware and software.
Horizontal up-sampling and filtering is done with a programmable, 7-tap polyphase filter
bank for accurate non-integer interpolations. Vertical scaling is achieved by repeating
and dropping lines in accordance with the applicable scaling ratio.
Video Timing
The video bus can be clocked either by double pixel clock, and clock qualifier or by a
single pixel clock. The double clock typically is used for TV displays, the single for
computer displays.
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